The present invention relates generally to a fluid dispensing system and method and, more particularly, to a sealant delivery system and apparatus for application of a sealant compound material to non-circular container closures.
It is conventional to apply sealant to the underside of container closure members in order to facilitate subsequent sealing attachment of the closure members to containers. Such sealant is normally applied in an annular pattern on the underside of each closure member in a manner such that, when the closure is attached to the container, the applied sealant will be located between the container rim and the closure member and, thus, seal the closure to the container.
One example of such a container closure is a can lid or xe2x80x9cendxe2x80x9d, as it is often referred to in the can-making industry. During the manufacture of a can end, a sealant, such as a latex sealant, is conventionally applied to the underside of a curl region of the end. After the can is filled, the end is seamed onto the upper flange of the can and the previously applied sealant material facilitates sealing between the curl area of the end and the flange of the can to which it is attached in order to prevent leakage.
Another example of such a container closure is a bottle cap or xe2x80x9ccrownxe2x80x9d, as it is often referred to in the bottling industry. In a similar manner to the can end described above, bottle crowns are conventionally provided with a sealant material such that, when the crown is subsequently attached to a filled bottle, the sealant material will be located between the crown and the bottle, thus facilitating sealing attachment of the crown to the bottle.
To apply sealant to a container closure in a manner as described above, a sealant dispensing apparatus is generally used. Such an apparatus is often referred to in the industry, and may be referred to herein, as a xe2x80x9csealant dispensing gunxe2x80x9d or simply a xe2x80x9cgunxe2x80x9d. Such sealant dispensing guns typically include a supply line which supplies liquid sealant to the gun, and a valve, such as a needle valve, for allowing the liquid sealant to be selectively dispensed from the gun. A container closure is generally supported by a chuck member which locates the closure adjacent the gun in the desired position. The closure is then rotated at a high speed by the chuck while the sealant dispensing gun valve is opened, thus resulting in an arcuate, even application of liquid sealant onto the underside of the closure. After application, the liquid sealant cures to form a solidified ring of resilient sealing material.
The extent of the rotational coverage of sealant on the closure may be adjusted by controlling the valve xe2x80x9cdwell timexe2x80x9d which is a measure of the time that the valve remains in its open position. Rotational coverage of a closure member with sealant is dictated by the valve dwell time relative to the rotational speed of the chuck and attached closure member. The dispense rate of sealant through the valve may also be controlled by adjusting the extent to which the needle valve opens.
Sealant dispensing guns are conventionally found in either stationary, indexing machines or in rotary machines. In an indexing machine, a sealant dispensing gun is stationarily mounted while the container closures to be coated are indexed through the machine. An example of such an indexing sealant dispensing machine for applying sealant to bottle crowns is described in U.S. Pat. No. 3,412,971 of McDivitt for ELECTRICALLY-CONTROLLED VALVE APPARATUS AND CONTROL CIRCUIT SUITABLE FOR USE THEREIN, which is hereby incorporated by reference for all that is disclosed therein.
In a rotary machine, a plurality of sealant dispensing guns are generally revolvingly mounted with respect to an axis. A rotary closure member feed mechanism is provided having a series of pockets which locate a closure member beneath each of the rotating guns. Each of the closure members is then sequentially lifted, engaged by a chuck member and rotated while the adjacent sealant dispensing gun applies sealant thereto. Examples of rotary sealant dispensing machines are set forth in U.S. Pat. Nos. 4,262,629 of McConnellogue et al. for APPARATUS FOR APPLICATION OF SEALANT TO CAN LIDS; 4,840,138 of Stirbis for FLUID DISPENSING SYSTEM; 5,215,587 of McConnellogue et al. for SEALANT APPLICATOR FOR CAN LIDS; 5,749,969 of Kobak et al. for FLUID DISPENSING SYSTEM; 6,010,740 of Rutledge et al. for FLUID DISPENSING SYSTEM and 6,113,333 of Rutledge et al. for APPARATUS AND METHOD FOR APPLYING SEALANT TO A CAN LID, which are all hereby incorporated by reference for all that is disclosed therein.
Some sealant dispensing guns include valves which are operated by cams and mechanical linkage arrangements. In these types of machines, the valve dwell time and the valve open limit are generally dictated by the specific physical cam and cam follower arrangement used. Accordingly, adjusting the valve dwell time or valve open limit in such machines generally requires a time consuming and expensive process of replacing various mechanical elements. Examples of such mechanical actuation arrangements are illustrated in U.S. Pat. Nos. 4,262,629 and 4,840,138, referenced above.
More common in recent years, however, are sealant dispensing guns in which the sealant dispensing gun valve is actuated by an electrical solenoid device or devices. In such guns, the valve dwell time is dictated not by mechanical linkages and cams, but instead by the amount of time that the valve opening solenoid is energized. Accordingly, the use of such electrical solenoid devices allows the valve dwell time of a sealant dispensing gun to be easily varied. Examples of sealant dispensing guns utilizing electrical solenoid valve actuation devices are illustrated in U.S. Pat. Nos. 3,412,971; 5,215,587 and 5,749,969, as previously referenced.
Since the cam actuation mechanism is eliminated in sealant dispensing guns having solenoid valve actuation devices, this type of gun generally also includes an adjustable mechanism for controlling the valve open limit. This adjustable mechanism may control the valve open limit by providing a movable stop for the valve stem or by moving the valve opening solenoid itself, or both.
In addition to solenoid valve actuation, some sealant dispensing guns also employ solenoid or motor actuated devices to adjust the valve open limit. Such guns allow remote control of the open limit and, thus, the rate at which sealant is dispensed from the gun when the valve is in its open position. Examples of sealant dispensing guns incorporating solenoid or motor actuated valve open limit devices are illustrated in U.S. Pat. Nos. 5,215,587 and 5,749,969, as previously referenced.
Although many closure members are circular, e.g., most soft drink can closure members, many closure members are irregularly shaped, i.e., are non-circular. Although the sealant dispensing systems described above generally work well, none of them are capable of applying sealant to irregular, i.e., non-circular, closure members. Accordingly, a need exists to provide a sealant dispensing system capable of applying sealant to irregular closure members.
Many existing sealant dispensing machines include magnets to assist in locating closure members on the machine when ferrous, e.g, steel, closure members, are to be coated with sealant. The magnets are generally located in conjunction with the chuck members such that the magnets tend to assist in locating the ferrous closure members on the chucks and maintaining them in place while sealant is applied. It has been found, however, that such magnets sometimes hinder the ability to remove the closure members from the chucks when coating has been completed.
In a stationary, indexing type machine, a shuttle mechanism typically serves to sequentially move uncoated closure members from a supply of closure members to the chuck of the sealant application mechanism. One limitation on the speed of an indexing machine is the length of time required to move a closure member into place on the chuck. Typically an indexing machine shuttle mechanism is driven by a crank device which, in turn, is driven by the main machine drive unit. The use of such a crank device inherently limits the speed of the shuttle mechanism and, thus, ultimately limits the speed at which the indexing type machine can operate.
Thus, it would be generally desirable to provide an apparatus and method which overcomes these problems associated with sealant dispensing devices as described above.
A sealant dispensing system is disclosed which is capable of applying sealant material to irregularly shaped, i.e., non-circular, closure members. To accomplish this, the closure member is loaded onto a rotary chuck in a conventional manner. The sealant applying gun, however, is moveable relative to the closure member. In this manner, through a combination of rotation of the closure member and movement of the gun, the gun is able to follow the outline of a closure member of any shape. To accomplish this, the gun may be mounted for pivotal movement. Alternatively, the gun may be mounted to allow translational, i.e., substantially linear movement. In either case, the movement may be achieved through the use of a servo motor. Alternatively, the movement may be achieved through the use of a linear actuator, such as a linear electromagnetic actuator.
In order to allow non-circular closure members to be loaded onto a chuck, the chuck must first be stopped. After the closure member is loaded, chuck rotation is then initiated. In order to allow this selective chuck rotation, the chuck may be attached to a servo motor.
An electromagnet may be located in proximity to each chuck of the sealant dispensing system. In this manner, the electromagnet may be activated during loading of the end of the closure member onto the chuck and then deactivated when it is time to unload the closure member from the chuck. Power to the electromagnet may be maintained during sealant application in order to ensure that the closure member remains in place on the chuck.
In an indexing type sealant dispensing system, the shuttle mechanism may be driven by a cam device, rather than a conventional crank mechanism. The cam device allows the motion characteristics of the shuttle mechanism to be precisely controlled such that machine cycle time can be reduced.